Cooling duct for a piston of a combustion engine

ABSTRACT

Disclosed is a cooling duct ( 6 ) for a piston ( 1 ) of a combustion engine. The cooling duct ( 6 ) has an annular shape and comprises two openings ( 7, 8 ) which are arranged next to each other and are alternately used as inlets as well as at least one outlet ( 15, 16 ) on the side of the cooling duct ( 6 ) located radially opposite the openings ( 7, 8 ). In order to allow the oil to more easily flow through the cooling duct ( 6 ) and thus the piston ( 1 ) to be better cooled, the cooling duct ( 6 ) has two outlets ( 15, 16 ) that are arranged next to each other as well as a reduced cross-section ( 17 ) which lies between the two outlets and acts as a throttle.

The invention relates to a cooling channel of a piston for an internalcombustion engine, in accordance with the preamble of the claim.

A cooling channel for a piston of an internal combustion engine is knownfrom the European patent EP 1 063 409 B1, which channel has two openingsthat are disposed next to one another and are intended to be alternatelyused as inflow openings, and an outflow opening disposed on the side ofthe cooling channel that lies radially opposite these openings. It isdisadvantageous, in this connection, that the oil introduced into thecooling channel flows through the cooling channel at a very high flowvelocity, whereby only a small part of the oil flows out by way of theoutflow opening, and the rest continues to flow, at a high flowvelocity, to the second opening, alternately used as an inflow opening,and flows out of the cooling channel by way of this opening. If the oiloutflow is stopped by the oil jet that impacts this second opening,because of a changed position of the piston, so that now oil can beintroduced into the cooling channel by way of this opening, eddies occurin the oil, which hinder the oil flow in the channel and thus cause thecooling effect of the oil to deteriorate.

It is the task of the invention to avoid this disadvantage of the stateof the art. This task is accomplished with the characteristics standingin the characterizing part of the claim.

The invention will be described in the following, using the drawing.This shows the cooling channel according to the invention, disposed in apiston for an internal combustion engine.

In the FIGURE, a piston 1 for an internal combustion engine is shown,having a ring belt 2, a piston crown 3, a piston skirt 4 that followsthe ring belt 2 on the side facing away from the piston crown, and a pinbore 5 for a piston pin not shown in the FIGURE.

A ring-shaped cooling channel 6 is disposed close to the piston crown 3of the piston 1, radially on the outside, which channel has two openings7 and 8 on one side, which openings are connected with the ring-shapedpart of the cooling channel 6 by way of a channel bend 9 and 10 in theshape of a quarter circle, in each instance, and face in the directionfacing away from the piston crown. The openings 7 and 8 alternatelyserve as inflow openings or as outflow openings for oil 12 sprayed inthe direction of the openings 7 and 8 by an oil nozzle 11.

In the FIGURE, the piston 1 is shown in a position that corresponds tothe upper dead center of the piston 1. In this connection, the oil jet12, which is directed at a slant with reference to the piston axis 13,impacts the opening 8, which therefore functions as an inflow opening.If the piston 1 moves downward, in the direction of the arrow 14, withinthe scope of the combustion or intake stroke, the opening 7 is impactedby the oil jet 12 starting from a specific piston position, so that thenthis opening 7 functions as an inflow opening for the oil 12.

On the side that lies radially opposite the openings 7 and 8, thecooling channel 6 has two outflow openings 15 and 16 that face in thedirection facing away from the piston crown. Between the outflowopenings 15 and 16, the cooling channel 6 has a cross-section narrowing17 that acts as a throttle.

The throttle 17 brings about the result, for one thing, that part of theoil 12 sprayed into the opening 8 in the position of the piston 1 shownin the FIGURE is passed out of the outflow opening 16, and, for another,that the flow of the oil that continues to flow through the left half ofthe cooling channel 6 is slowed down, which has the effect that noeddies that would hinder the oil inflow by way of the opening 7, intothe left half of the cooling channel 6, form in the oil in the left halfof the cooling channel 6, when the piston 1 moves downward in thedirection of the arrow 14, whereby the opening 7 gets into the jet pathof the oil 12, in order to then function as an inflow opening. In thisconnection, oil then flows through the left half of the cooling channel6 by way of the opening 7, and part of this oil flows out of the outflowopening 15 because of the throttle 17, and the rest continues to flowthrough the right half of the cooling channel 6, at a slower velocity,because of the throttle 17, in order to flow out of the opening 8. Inthis way, a rapid change in the oil flow direction in the coolingchannel 6 and thus improved cooling of the piston 1 are achieved.

REFERENCE SYMBOL LIST

-   1 piston-   2 ring belt-   3 piston crown-   4 piston skirt-   5 pin bore-   6 cooling channel-   7, 8 opening-   9, 10 channel bend-   11 oil nozzle-   12 oil, oil jet-   13 piston axis-   14 arrow-   15, 16 outflow opening-   17 cross-section narrowing, throttle

1. Cooling channel (6) of a piston (1) for an internal combustionengine, having a piston crown (3) and a ring belt (2), wherein thecooling channel (6) is configured in ring shape and is disposed close tothe piston crown (3) of the piston (1), radially on the outside, closeto its ring belt (2), and has two openings (7, 8) that are disposed nextto one another and are intended to be alternately used as inflowopenings, and at least one outflow opening (15, 16) disposed on the sideof the cooling channel (6) that lies radially opposite the openings (7,8), wherein the cooling channel (6) has two outflow openings (15, 16)disposed next to one another, and a cross-section narrowing (17)disposed between them, which acts as a throttle.